Thermally controlled automatic door closer



J. H. DERBY THERMALLY CONTROLLED AUTOMATIC noon CLOSER Filed Feb. 9, 1938 m INVENTOR Io/0v bf- D528) (54 AT TOZ N EYS Patented Oct. 24, 1939 UNITED STATES PATENT OFFICE THERMALLY CONTROLLED AUTOMATIC DOOR CLOSER 5 Claims.

This invention relates to automatic door closers and checks of the type which has means for retaining the door closing mechanism yieldingly against operation when the door has been opened to a predetermined position and a general object of the invention is to provide improved thermally-controlled means for releasing the retaining means of such a door-closing mechanism when the temperature in the region of the door 4 exceeds a desired maximum.

One of the most effective means for preventing the rapid spread of conflagrations is to be sure that the doors which shut off separate sections of a building are closed when or immediately after a fire starts. This is particularly important, of course, if, as in most modern buildings, the doors, particularly between offices or lofts and hallways, are of fire-resisting construction.

It is customary in ofiice and loft buildings to provide doors with spring-operated door closers,

usually associated with checks, such as dash pots. In most cases these door closers are so constructed that they may be set for a predetermined open-door position in which they will yieldingly retain the door in this predetermined open position against the normal tendency of the spring to close it. When a door is thus left it is, of

course, not furnishing the desired protection against the spread of a confiagration in the build- Various attempts have been made to rovide for automatic release of the retaining means in such door closers when a fire starts, but for the most part these means have been complicated and unreliable, the unreliability growing largely out of the complication which has rendered the mechanism susceptible to accumulation of dirt, corrosion and other things tending to interfere with its operation when operation is important.

The present invention aims particularly to provide simple and reliable means for releasing the retaining means in .door closers of the type having means for retaining them yieldingly in open position, which releasing means shall be so constructed and arranged that it will not become ineffective for its purpose even though unused for said purpose over many years.

An important feature of the invention is the confinement of the movable parts of the releasing mechanism in a casing which is substantially dust and moisture proof and in which they can be maintained in permanently lubricated condition and thus sure to operate when operation is important.

Other objects and important features of the invention will appear from the following description and claims when considered in connection with the accompanying drawing in which Figure 1 is a plan view of a door closer and check of the horizontal swinging arm type in position on a door and having attached thereto a preferred embodiment of the present invention;

Figure 2 is a side elevation of the door and check shown in Figure 1;

Figure 3 is an enlarged detail view with the spring and plunger casing shown in section on the line 33 of Fig. 4, and

Figure 4 is an enlarged plan view of the door closer and check having the invention incorporated therein. 1

In the illustrative embodiment of the invention the door closing mechanism is of an ordinary commercial type comprising a horizontally swinging arm 2 carried upon the upper end of a vertical shaft 4 extending through a spring housing 6 into a dash-pot housing 8, the spring housing 6 having therein a spiral spring ill which is under tension when the door is closed and the tension of which is increased, as the door I2 is opened, through a link connection 54 between the end of the swinging arm 2 and the door casing H5. The spring housing 5 is provided with a cap 18 having therein a depression 20 for receiving the spherical lower end of a spring pressed plunger 22 which, when it is received in the depression 20 ofiers resistance to the tendency of the spring Hi to swing the arm 2 horizontally sufiicient to hold the door H2 in its open position. The cap I8 is usually provided with spanner notches 24 so that it can be turned on the spring housing 6 into various open-door adjustments.

As herein shown, the plunger 22 is guided in an opening 24 in the bottom of a casing or housing 26 threaded at its lower end and screwed into a correspondingly threaded hole 28 tapped through the arm 2. A flange 38 serves so to position the casing 2 that its under side is substantially flush with the under side of the arm 2. At its upper end the casing 26 is closed by an internally screw-threaded cap 32 integral with a yoke 34 which carries the abutment for the thermostatio element hereinafter to be described. The cap 32 is provided with an opening 36 into which extends the upper end of a second plunger 38 provided with a flange 4G and a central boss 42 extending into the upper end of the spring 44. The plunger 38, when held stationary Ill by the thermostatic element hereinafter to be described, constitutes a part of the stationary abutment which takes up the counter-thrust of the spring 42 when tensioned to exert a downward pressure on the plunger 22, the lower end of the spring d4 resting on the fiange ifi of the plunger 22 and being centered by a boss 58.

For convenience in manufacture and adjustment, the abutment for the thermostatic element is preferably made in the form of a threaded short bolt or screw 50 provided with a recess 52 in its lower end and adapted to be screwed into the opening 54 tapped through the enlarged upper end 56 of the yoke 34. A look nut 58 may be used to secure the abutment member 50 in its adjusted position.

The thermostatic element 6!] serves as a strut between the abutment 52 and the recessed upper end 62 of the plunger 38. Any suitable thermostatic element may be used for this purpose. Of the thermostatic elements now available for such purposes, however, it has been found that the small sealed cell or bulb of quartz or quartzoid material, containing a readily expansible liquid such, for example, as carbon tetrachloride, is most satisfactory because it is not subject to corrosion and is comparatively unaffected by exposure to conditions where dust accumulates. The thermostatic element 58 is, therefore, preferably a cell or bulb of the type which explodes when the temperature exceeds that for which the bulb has been calibrated, the release resulting from the cracking of the cell or bulb due to the expansion of the liquid being accelerated by hav ing the cell or bulb under pressure, as in the present case.

As herein shown, the tension on the spring M which causes the spring to exert a constant downward pressure on the plunger 22 is maintained by the cell or bulb 69 serving as a strut to hold the plunger 38 in the position shown in Fig. 3. This tension in practice may be in the neighborhood of 25 lbs. and this pressure on the cell or bulb 60 accelerates its shattering when the temperature reaches the critical point.

The operation of the device will be apparent from the foregoing description but may be briefly recapitulated as follows:

The parts being in the position shown in Figure 1 and also in Figure 3, with the plunger 22 resting in the depression in the cap is and. maintained in the depression under the pressure of the spring M which, as above suggested, is exerting a downward pressure of about 25 lbs, the door will remain in the position shown in Figure 1 unless moved by hand with sufficient force to cause the plunger 22 to ride up out of .the depression 20. If, however, there is a sudden rise in temperature occasioned by the start of a fire, the expansion of the liquid in the cell Gil will cause it to crack its quartz or quartzoid container and the upward pressure exerted by the spring 4 3 on the cell Bil through the plunger 38 will cause the sudden complete shattering of the cell 69 and thus the release of the plunger 38 which will move up through the opening 36 in the cap 32, thereby relieving the tension on the spring 44 and at the same time relieving the pressure of the spring 14 on the plunger 22, so that it will no longer act to hold the door l2 in its open position against the tendency of the spring Iii to move the arm 2 in its door-closing direction.

To reduce strain on the cell 60 during the ordinary door operations ring packing 64 may be so placed in the recesses 52 and 62 as to prevent direct engagement of the cell 69 with the metal.

To prevent dust from entering the casing 26 and to insure free movement of the plungers 22 and 38, the interior of the casing 25 will preferably be packed with graphite or other suitable permanent lubricant. Preferably, also a felt washer 66 will surround the end of the plunger 38 which projects above the upper face of the cap 32.

It will be understood also that the operating parts will preferably be made of non-corrodable materials as well as being protected by the lubricant.

What is claimed as new is:

1. An automatic door closer having, in combination, a horizontally swinging spring-actuated arm, a vertically movable spring-pressed plunger for yieldingly retaining said arm in a predetermined open-door position, a casing in which said plunger spring is confined and through one end of which said plunger projects, a second plunger normally forming an abutment for said spring and slidable through the other end of said casing when unbraced, an open yoke on the last-mentioned end of said casing having an abutment thereon, and a thermally explodable frangible cell, substantially filled with a readily expansible fluid, which constitutes a plunger-bracing strut between said second plunger and said abutment, said casing and parts carried thereby being 1 cmovable from and attachable to said arm as a unit.

2. An automatic door closer having, in combination, a horizontally swinging spring-actuated arm, a vertically movable spring-pressed plunger for yieldingly retaining said arm in a predetermined open-door position, a casing in which said plunger spring is confined and through one end of which said plunger projects, a second plunger normally forming an abutment for said spring and slidable through the other end of said casing when unbraced, an open yoke on the last-mentioned end of said casing having an abutment thereon, a thermally explodable frangible cell, substantially filled with a readily expansible fluid, which constitutes a plunger-bracing strut between said second plunger and said abutment, and a moisture and dust excluding permanent lubricant filling said casing, said casing and parts carried thereby being removable from and at: tachable to said arm as a unit.

3. An automatic door closer having, in combination, a horizontally swinging spring-actuated arm, a spring-pressed plunger movable transversely to said arm for yieldingly retaining said arm in a predetermined open-door position, a casing forming a housing and guide for said spring and plunger, and means carried by said casing which serves as a normally stationary abutment for said plunger spring, said means including a thermally explodable frangible cell, approximately filled with a readily expansible fluid and constituting a strut interposed between said spring and a permanent part of said means, said casing and the parts carried thereby being removable from and attachable to said arm as a unit.

4. An automatic door closer having, in combination, a horizontally swinging spring-actuated arm, a spring-pressed plunger movable transversely to said arm for yieldingly retaining said arm in a predetermined open-door position, a casing forming a housing and guide for said spring which serves as a normally stationary abutment for said plunger spring, said means including a thermally explodable frangible cell, substantially filled with a readily expansible fluid, interposed between said spring and a permanent part of said means, said casing and the parts carried thereby being removable from their operative relation to said arm and attachable in operative relation thereto as a unit.

5. An automatic door closer having, in combination, a horizontally swinging spring-actuated arm, a spring-pressed plunger movable transversely to said arm for yieldingly retaining said arm in a predetermined open-door position, 'means serving as a stationary abutment for said plunger spring, said means including a thermally explodable frangible cell, substantially filled with a readily expansible fluid, which constitutes a collapsible strut interposed between said spring and a permanent part of said means, and a casing in which said spring is confined and through one end of which said plunger projects, the permanent part of said stationary abutment comprising an open framework connected to and carried by said casing and located, when the parts are in operative position, at one side of and clear of said arm and in which framework said thermally explodable cell is immediately exposed to temperature changes, said casing and the parts carried thereby being attachable to said arm in operative relation thereto and removable from its operative relation thereto as a unit.

JOHN H. DERBY. 

